1. Field of the Invention
The invention relates generally to devices and methods for providing low-cost, low-power, secure voice communications, and more particularly to devices and methods for providing direct secure voice communication between an initiator device and one or more recipient devices without the use of an intermediate network.
2. Description of the Related Art
Handheld radio transceivers (e.g., walki talkies) have existed for many years and have provided communication amongst multiple users on the premises of construction sites, factories, warehouses and other facilities. These radio transceivers include a memory that may be loaded with a predetermined sequence or listing of channel and sub-channel codes to provide selective calling operations. The sub-channel can be referred to as digital coded squelch (DCS) or continuous tone-coded squelch system (CTCSS), which are a set of codes that are programmed into each radio transceiver so that multiple radio transceivers with the same code can communicate with each other. For example, two different transceivers can be manually set to channel 5 and sub-channel 17, thus allowing the two transceivers the ability to communicate with each other. Once the transceivers are set to the same channel and sub-channel, one user can press the push-to-talk (PTT) button to begin communication with the other user.
The number of communication channels available, however, is necessarily limited by the number of frequencies allotted for use by the Federal Communications Commission (FCC). For example, the FCC has allotted only 14 channels to consumers to operate two-way radio products without a radio license (sometimes referred to as the Family Radio Service (FRS)).
One drawback of conventional transceivers is their inability to provide private communications when multiple users are communicating in a densely populated area. Therefore, if multiple users are in the same area, it maybe difficult for the users to select an available secure channel for communication. Another drawback of conventional transceivers is the inability to switch the transceivers to another channel during interference. For example, if two transceivers are on channel 4, sub-channel 26 and interference occurs preventing the users from communicating, the users will not be able to switch to the same channel because they are unable to communicate that information to each other. That is, one user must be able to notify the other user of the channel to switch to. Thus, the problem of reconnecting to another channel exists.
Thus, it should be appreciated that there is a need for low-cost, low-power and secure devices and methods that allow multiple users the ability to communicate with one another while preventing third parties within the specified range from listening to the conversation. The invention fulfills this need as well as others.